Heavy oils require a substantial amount of cracking in order to be economically refined to produce usable products. One major problem affecting the economics of refining heavy oils is the fact that many of these oils contain metal compounds which poison the catalysts used to crack the oil. If heavy oils could be upgraded without sacrificing the usable product yield or without adversely affecting the economics of oil refining as catalyst poisoning does, many new sources of oil products could be developed in the western hemisphere.
Vanadium is present in high concentrations in the Boscan crude oil, and a significant amount of this metal exists in the crude in the form of vanadyl porphyrin chelates. Since porphyrins are detectable in crude oils even at low concentrations using ultraviolet-visible spectrum analysis, and since the vanadyl porphyrins are notorious for their stability and survivability, vanadyl porphyrin behavior and atomic vanadium balances can be used to determine the metal's behavior in the refining of Boscan crude oil.
An alternative oil source that could be used to provide oil products is tar sands. However, the tar sand resources generally produce a heavy oil product that also requires significant upgrading to produce usable products. The high costs of mining the tar sand, extracting the raw tar sand bitumen, and refining the tar sand bitumen to produce salable products are major economic obstacles to be overcome before commercial development of most tar sand resources can occur.
If the technology could be developed to upgrade these heavy crude oils economically without sacrificing the product oil yield, both heavy crude oil and tar sand derived oil could be economically delivered to consumers in the United States. New processing technologies are needed to increase oil yield from heavy oil and tar sands, wherein a minimum of upgrading for these products is required, and high value by-products can be generated during the processing.
Experiments have been conducted using a recycle oil pyrolysis process extraction process with Asphalt Ridge tar sand and heavy oil which show that high yields of light oil products, similar to products generated in crude oil refining, can be obtained from these resources. Additionally, the heavy oil residue from this process contains a high concentration of nitrogen and asphaltenes, which are desirable for asphalt binders.
The operating conditions of the process also create an environment where compounds containing metals can be removed by deposition on the spent tar sand. The spent tar sand then becomes a suitable source for production of these metals. The lower selling price of heavy oil as compared to lighter oils, the creation of valuable by-products, and the ability to remove metals from the heavy oil result in a process with improved commercial potential for these resources at lower financial risk.
A number of processes have been designed to remove heavy metals from crude oil, with varying degrees of success
Ueda et al., in U.S. Pat. No. 3,936,371, disclose a method for removing vanadium, nickel, sulfur, and asphaltenes from heavy hydrocarbon oil by contacting the heavy oil with red mud and maintaining this mixture at elevated temperatures in the presence of hydrogen.
Kirkbride, in U.S. Pat. No. 4,234,402, discloses a process for removing sulfur from coal or petroleum comprising drying the coal and subjecting the dried coal in a hydrogen atmosphere to the influence of wave energy in the microwave range.
Mekler, in U.S. Pat. No. 1,897,617, discloses a process for refining hydrocarbon distillates containing mercaptans by subjecting the distillate to the action of X-rays.